188O EMERALD trial analysis of patient-reported outcomes (PROs) in patients with ER+/HER2− advanced or metastatic breast cancer (mBC) comparing oral elacestrant vs standard of care (SoC) endocrine therapy

The phase III EMERALD trial (NCT03778931) reported significantly prolonged progression-free survival (PFS) and a manageable safety profile with elacestrant vs SoC endocrine therapy (ET) in patients (N=478) with ER+/HER2− advanced or mBC following progression on prior CDK4/6i plus ET. PROs measuring quality of life (QoL) are reported here. EMERALD patients (pts) completed 3 PRO tools at prespecified time points: the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30), the PRO version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE), and the EuroQoL 5 Dimension 5 Level (EQ-5D-5L). The ratio of PROs tools completed vs. PROs tools expected was 80-90% through cycle 4 and approximately 70% at cycle 6; likely due to clinical study period overlapping with COVID-19 period. Overall, the EORTC QLQ-C30 scores were similar for elacestrant and SoC, with no differences across all time points for both functional and symptom scales. However, PRO-CTCAE results showed that fewer pts who received elacestrant reported very severe nausea (4.0% vs 14.3% by cycle 6) or very severe vomiting (9.1% vs 50% by cycle 6) compared with SoC. There were no clinically meaningful differences across all time points in adverse events typically observed with pts with cancer on ET, such as fatigue, nausea, vomiting, joint and muscle pain and hot flashes. EQ-5D-5L scores were generally comparable throughout treatment for both study arms, with elacestrant showing numerically better outcomes vs SoC for mobility, self-care and usual activities. Similar trends were observed for the full intent-to-treat population and in pts with detectable estrogen receptor 1 mutations (ESR1m). This analysis confirmed that QoL was maintained between treatment groups in the EMERALD trial. Together with the previously described statistically significant prolonged PFS and manageable safety profile, these PRO results provide additional evidence that oral elacestrant is clinically meaningful in this patient population with limited therapeutic options.